This research proposal has two objectives. First, the development of methods for detecting and identifying materials of biological and clinical importance, with present emphasis on the substances involved in uremia and hemodialysis. These methods utilize highly sophisticated, sensitive, and informative contemporary techniques of analysis such as mass spectrometry, gas and liquid chromatography, and nuclear magnetic resonance spectrometry. Second, the determination of the conformations of biopolymers in solution and the determination of the extent and nature of the interactions in solution of biopolymers with various entities of biological importance. These studies include synthesis of isotopically labeled and modified peptides, application of advanced nuclear magnetic spectrometric techiques, and a variety of additional physical and chemical measurements.